Hi ALL, the C8051F020 on my own board can't be downloaded by JTAG, the schematic is listed below. I supose the keil program and adapter correct, since it can be download successfully by development board. Also, do IO ports affect successfully download? Please help, thanks！！！
Thank you ALL! The problem has already solved, stuppid me, the reset is low power enable, my schematic mislead myself. Below is the proper datasheet of C8051F020!